Drill attachment



Aug- 1, 1961 N. w. RISE DRILL ATTACHMENT Filed July 22, 1957 Vflll.

WN() NNI Wmv Unite States 2,994,235 DRILL ATTACHMENT Noble W. Rise, Detroit, Mich., assignor to Analytical Engineers, Inc., Detroit, Mich., a corporation of Michigan Filed July 22, 1957, Ser. No. 673,381 8`Claims. (Cl. 77-55) This invention relates to a drill attachment for controlling the feed rate of a hand-fed drill. Drills such as the usual electric hand drill, especially when used for drilling in thin metal, have a tendency to break through, as the hole is completed, in a manner which results in a non-circular hole with undesirable burrs and which frequently also results in drill breakage. These di'iculties, attendant upon properly feeding a hand-fed drill, particularly in going through thin metal work pieces, result from the operators inability to prevent a sudden advance motion as the feeding resistance slackens or disappears.

It is an object of the present invention to provide a drill attachment which will prevent sudden advance or jumping and thus eliminate these difficulties.

A further object is to provide a drill attachment having a piston and cylinder arrangement connected with a foot bracket which may be quickly placed in contact with the work and which will serve to control the rate of feed of the drill into and through the work.

Another object is to provide a drill attachment of this character wherein a hydraulic control means is utilized for restraining feeding movement of a hand-fed drill.

It is also an object to provide an attachment of this character in which the foot bracket may be readily adjusted to the proper position for the start of a drilling operation, and which will automatically lock in this position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing Wherein a preferred form of the present invention is illustrated.

In the drawing:

The single figure is a longitudinal sectional view of a drill attachment incorporating a preferred form of the present invention.

Referring now to the drawing, there is shown in the single figure a conventional electric hand drill designated 10 and indicated by dashed lines. 'Ille body of the drill 10 has a cylindrical nose section .12 concentric with and behind the chuck 14 which carries the drill bit 16, all of which are of conventional form.

The drill attachment of the present invention comprises a body 18 which has integrally formed thereon a bracket 20 which is shaped to lit the nose section 12 and is slotted at 22 so that it may be clamped together to tightly engage the nose section 12 by means of a clamping bolt 24.

Formed within the body 18 is a cylinder 26 which is open at both ends. A piston 28 is slideable within the cylinder 26 and is urged to the left by a spring 30. A suitable sliding oil seal 32 is provided near the right hand end of the piston 28. The piston 28 is provided with a keyway 34 for the reception of a stop screw 36 which serves to limit the outward motion of piston 28 and to prevent rotation thereof.

The piston 28 is provided with a central bore 38 within which is slideably mounted a rod 4t) which forms part of a foot bracket generally designated 42. The foot bracket 42 includes also a foot member 44 secured to the rod 48 by a pin 46 and having an opening 48 in which a drill bushing 50 may be removably positioned. The opening 48 and drill bushing 50 are located in alignment with the axis of the chuck 14 and drill 16.

The left hand end of piston 28 is reduced in diameter Patented Aug. .1, 1961 as indicated at 52 and carries clamped thereto a lock bracket 54. The bracket 54 is provided with an internal inclined cam surface 56 for coaction with a roller 58 which is urged to the right by a spring 60. The bracket 54 carries a plate 62 on its left hand face which holds the spring and roller in position and also co-operates with a flat 64 formed on the side of the rod 48 to permit sliding of the rod 40 in the bore 38 but to prevent its rotation. The flat 64 also provides a flat surface to be contacted by the roller 58. The bracket 54 is slotted at 66 to receive a roll-release lever 68 pivoted on a pin 70.

The body 18 is also provided with a lug 72 for contact with the drill 10, it being understood that the bracket 20 and the lug 72 are representative of but one of the many well-known ways by which the body 18 may be attached to the `drill 10. Also formed in the body 18 is a cylinder or chamber 74 which opens to the right hand end. A cylinder head 76 is secured by bolts, not shown, to the right hand end of the body `18 and serves to close both the cylinder 26 and the chamber 74.

A passage 78 is formed in the cylinder head 76 and communicates through a needle valve 80 with an elbow passage and pipe 82 which terminate centrally of the chamber 74. A flexible bellows 84 of synthetic rubber or similar flexible material is attached to the left hand end of the elbow pipe 82. A branch 86 containing a check valve 88 connects between the pipe 82 and the interior of cylinder 26 and provides free flow of liquid from the former to the latter irrespective of the amount of resistance imposed by the needle valve 80.

In operation, the cylinder 26, the chamber 84 and the connecting passageways are filled with suitable hydraulic oil. For this purpose, the needle valve 80 may be removed, thus providing a filling opening into which oil may be poured. With the spring 38 having extended the piston 28 to the extreme left hand position and With the flexible chamber 84 in a position of nearly complete collapse, the device may be readied for use by attaching it to the drill 10 as shown in the drawing, and by bringing the foot bracket rod 40 into its innermost position in bore 38 as is also shown in the drawing. For this purpose, the lever 68 may be depressed to release the roller 58 so as to permit free sliding of the rod 40 into the bore 38.

With drills of a length such as the drill 16 shown in the drawing, or shorter, the foot bracket 44 is positioned against the work piece 90 andthe drill is advanced into the workpiece manually. If on the other hand a longer drill 16 than the one shown in the drawing is used, the drill point is placed against the Work piece 90 and the foot bracket 44 is manually slid out of the bore 38 until the drill bushing 50 contacts the work piece.

As the drill is advanved into the work piece, the foot bracket 44 tends to be pushed into the bore 38. This, however, is prevented by the roller 58 which wedges between the inclined cam surface 56 and the flat 64 to create a one-way locking action automatically. The spring 60 insures that the roller is maintained in a camming position except when prevented by depression of the lever 68. Accordingly, the rst advance of the drill causes the piston 28 to be pushed into the cylinder 26 against the force of spring 38 and to drive the hydraulic oil through passages 78 and 82 into the chamber 84. The needle valve 80 is adjusted so that any desired action of resistance to such ow is created and thus the speed of advance of the drill is determined for any given amount of manually applied feeding pressure.

As the drill breaks through the work, the manual feeding pressure cannot possibly be instantly relieved. Any tendency of the drill to jump ahead at this time, however, is prevented by the piston 28 which would require that a much higher pressure be built up, in order that any significant increase in the rate of ilow through the needle valve 80 .take place. Thus, the piston 28 provides a substitute load resistance .for that formerly supplied by the work piece itself.

Upon completion of the drilling movement, the drill is manually removed and the spring 30 pushes the piston 2S outwardly las f-ast as the drill is retracted out of the hole. During this retraction movement of the drill, the oil flows from the expansible chamber 84 through passages 82 and 86 and check valve 88 which is a path of little resistance permitting rapid refilling of the cylinder 26.

It will thus be seen .that ythe present invention provides an improved drill attachment in which a foot bracket may be readily adjusted to contact a work piece and serve to actuate a hydraulic system which imposes a predetermined adjustable resistance to the rapid `'advancing of the drill into and through the work.

Although the attachment has been shown and described in connection with a hand-held drill, it will be understood that the same attachment may be fused on a drill press of the hand-fed type by securing it to the translatable quill thereof.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all corning within the scope of the claims which follow.

What is claimed is las follows:

1. A unitary feed control attachment for a rotary drill comprising a body having a bracket for attachment to a hand-held drill, a cylinder element and a piston element slideable therein, one of the elements being associated with the body, the other element having a foot bracket slideably associated therewith, means including a detent of the self-engaging type for locking the foot bracket to said other element in various positions of relative eXtension and hydraulic means for limiting the speed of feeding of the dnill towards a work piece when the foot bracket is in contact therewith, the hydraulic means including an expansible chamber connected with the cylinder and means for controlling the rate of flow between the cylinder Aand the chamber.

2. A unitary feed control attachment for a rotary drill comprising a body having a bracket for attachment to a hand-held drill, a cylinder element and a piston element slideable therein, one of the elements being associated with the body, the other element having a foot bracket slideably associated therewith, means including a spring biased frictionally wedging detent for locking the foot bracket to said other element in various positions of relative extension and hydraulic means for limiting the speed 'of feeding of the drill towards a work piece when the foot bracket is in contact therewith, the hydraulic means including an expansible chamber connected with the cylinder and means for controlling the rate of flow between f the cylinder and the chamber.

3. A unitary feed control attachment for a rotary drill comprising a body having a bracket for attachment to a hand-held drill, a cylinder element and a piston element slideable therein, one of the elements` being associated with the body, the other element having a foot bracket slideably yassociated therewith, means including a spring loaded roller and ian inclined cam track for locking the foot bracket to said other element in various positions of relative extension and hydraulic means for limiting the speed of feeding of the drill towards -a work piece when the foot bracket is in contact therewith, the hydraulic means including an expansible chamber connected with the cylinder and means for controlling the rate of flow between the cylinder and the chamber.

4. A unitary feed control attachment for a rotary drill comprising a body having a bracket for attachment to a hand-held drill, `a cylinder element and a piston element slideable therein, one of the elements "being associated with the body, the other element having a foot bracket and hydraulic means for limiting the speed of feeding of the drill towards a work piece when the foot bracket is in Contact therewith, the hydraulic means including a exible walled chamber connected with the cylinder and means for controlling the rate of ow between the cylinder land. the chamber.

5. A unitary feed control attachment for a rotary drill comprising a body having a bracket for attachment to a hand-held drill, a cylinder element and a piston element slideable therein, one of the elements being associated with the body, the other element having a foot bracket slideably associated therewith, means including a spring loaded roller and an inclined cam track for locking the foot bracket to said other element in various positions of relative extension and hydraulic means for limiting the speed of feeding of the drill towards a work piece when the foot bracket is in contact therewith, the hydraulic means including a iiexible walled chamber connected with the cylinder and means for controlling the rate of flow between the cylinder and the chambers.

6. A unitary feed control for a rotary drill comprising a body having a bracket vfor fixedly attaching the body to a non-rotating part of the drill, said body also including a cylinder element and a piston element slidable in rthe cylinder element, one of said elements being iixedly associated with the body and the other element having a foot bracket associated therewith, the arrangement being such that when the body is attached to a drlil and the foot bracket is engaged against the Work piece to be drilled, movement of the drill in a direction toward the work piece .causes movement of the piston element inwardly relative to the cylinder element, and means for limiting the rate of fluid displaced from the cylinder element in response to movement of the piston element inwardly thereof .to limit the speed of feed of the drill toward the work piece, said last mentioned `means including a needle valve and acheck valve in parallel therewith, said check valve being biased to normally vprevent the displacement yof fluid from lthe cylinder, and `a spring normally biasing said piston element outwardly of the cylinder element, said check valve and said needle valve communicating with an expansible chamber.

7. A unitary feed control for a rotary drill comprising a body having a bracket for iXedly attaching the body to a non-rotating part of the drill, said body also including a cylinder element and a piston element slidable in the cylinder element, one of 4said elements being tixedly associated with lthe body and the other element having a foot bracket associated therewith, the arrangement being such that when the body is `attached to a drill and the foot bracket is engaged against the work piece to be drilled, movement of the drill in a direction toward the work piece causes movement of the piston element inwardly relative to the cylinder element, and means for limiting the rate of fluid displaced from the cylinder element in response to movement of the piston element inwardly thereof o limit the speed of feed of the drill toward the work piece, said foot bracket being slidably associated with said other element and means for locking said foot bracket in various positions of extension relative to said other element, said last mentioned means comprising a springloaded roller and an inclined cam track in wedge locking relation and means for moving the roller against the tension of the spring to release the wedge lock and permit said foot bracket to slide relative to said other element.

8. A unitary feed control attachment for a rotary drill comprising a body having a bracket for tixedly attaching the body to a non-rotating part of the drill, said body having a cylinder thereon, a piston slidable within said cylinder, said piston also having a cylinder extending axially therein, -a plunger slidably arranged within said second cylinder, said plunger having a foot bracket References Cited in the le of this patent UNITED STATES PATENTS Ellerstein Oct. 24, 1944 Gr-in Feb. 22, 1949 Timpner Oct. 7, 1952 Shaf Nov. 3, 1953 Timpner Apr. 13, 1954 Shulters et a1. Apr. 28, 1959 

